Surface currents measured by high frequency （HF） radar arrays are assimilated into a regional ocean model over Qingdao coastal waters based on Kalman filter method. A series of numerical experiments are per- formed ...Surface currents measured by high frequency （HF） radar arrays are assimilated into a regional ocean model over Qingdao coastal waters based on Kalman filter method. A series of numerical experiments are per- formed to evaluate the performance of the data assimilation schemes. In order to optimize the analysis pro- cedure in the traditional ensemble Kalman filter （ENKF）, a different analysis scheme called quasiensemble Kaman filter （QENKF） is proposed. The comparisons between the ENKF and the QENKF suggest that both them can improve the simulated error and the spatial structure. The estimations of the background error covariance （BEC） are also assessed by comparing three different methods： Monte Carlo method; Canadian quick covariance （CQC） method and data uncertainty engine （DUE） method. A significant reduction of the root-mean-square （RMS） errors between model results and the observations shows that the CQC method is able to better reproduce the error statistics for this coastal ocean model and the corresponding external forcing. In addition, the sensibility of the data assimilation system to the ensemble size is also analyzed by means of different scales of the ensemble size used in the experiments. It is found that given the balance of the computational cost and the forecasting accuracy, the ensemble size of 50 will be an appropriate choice in the Qingdao coastal waters.展开更多
A fine resolution model has been applied to get more insight into the effects of a modified runoff due to the Three-Gorges-Dam （TGD） on the East China Sea （ECS）.The region of interest was confined to the offshore ...A fine resolution model has been applied to get more insight into the effects of a modified runoff due to the Three-Gorges-Dam （TGD） on the East China Sea （ECS）.The region of interest was confined to the offshore area in the vicinity of the Changjiang River.To the east,it extended up to the area southwest of Cheju Island.The model was used to evaluate the effect of a modified runoff on the water properties of the adjacent regions like the Changjiang diluted water （CDW） and the Zhoushan Fishing Ground.The sensitivity of the ECS to a modified Changjiang runoff was explored firstly by sensitivity studies and secondly by experiments based on historical runoff records and water management plans of the TGD.These experiments led to the general conclusion that the most affected area by runoff is located close to the Changjiang River mouth.The area of influence has an extension of about 150 km×150 km.In the realistic experiment,the related anomalies reached their maximum value in early summer （May）.In normal years the related salinity anomalies can get to as large as 2.展开更多
基金The National High Technology Research and Development Program of China under contract No.2007AA09Z117the Science and Technology Project of the North China Sea Brach of SOA under contract No.2012A01the Joint BMBF-WTZ Project of China under contract No. CHN 09/031
文摘Surface currents measured by high frequency （HF） radar arrays are assimilated into a regional ocean model over Qingdao coastal waters based on Kalman filter method. A series of numerical experiments are per- formed to evaluate the performance of the data assimilation schemes. In order to optimize the analysis pro- cedure in the traditional ensemble Kalman filter （ENKF）, a different analysis scheme called quasiensemble Kaman filter （QENKF） is proposed. The comparisons between the ENKF and the QENKF suggest that both them can improve the simulated error and the spatial structure. The estimations of the background error covariance （BEC） are also assessed by comparing three different methods： Monte Carlo method; Canadian quick covariance （CQC） method and data uncertainty engine （DUE） method. A significant reduction of the root-mean-square （RMS） errors between model results and the observations shows that the CQC method is able to better reproduce the error statistics for this coastal ocean model and the corresponding external forcing. In addition, the sensibility of the data assimilation system to the ensemble size is also analyzed by means of different scales of the ensemble size used in the experiments. It is found that given the balance of the computational cost and the forecasting accuracy, the ensemble size of 50 will be an appropriate choice in the Qingdao coastal waters.
基金The Public Science and Technology Research Funds Projects of Ocean under contract Nos 200905001 and 201005019the Germany-China Cooperation in Marine Science and Technology under contract No.CHN 04/009+4 种基金the State Basic Research Program of China under contract No.2011CB409803the State Key Technology Research and Development Program of China under contract No.2008BAC42B03the Hi-tech Research Development Program of China under Grant No.2007AA09Z117the National Natural Science Foundation of China under contract No.40706018the Scientific Research Fund of the Second Institute of Oceanography,the State Oceanic Administration of China under contract Nos JT1105 and JT0903
文摘A fine resolution model has been applied to get more insight into the effects of a modified runoff due to the Three-Gorges-Dam （TGD） on the East China Sea （ECS）.The region of interest was confined to the offshore area in the vicinity of the Changjiang River.To the east,it extended up to the area southwest of Cheju Island.The model was used to evaluate the effect of a modified runoff on the water properties of the adjacent regions like the Changjiang diluted water （CDW） and the Zhoushan Fishing Ground.The sensitivity of the ECS to a modified Changjiang runoff was explored firstly by sensitivity studies and secondly by experiments based on historical runoff records and water management plans of the TGD.These experiments led to the general conclusion that the most affected area by runoff is located close to the Changjiang River mouth.The area of influence has an extension of about 150 km×150 km.In the realistic experiment,the related anomalies reached their maximum value in early summer （May）.In normal years the related salinity anomalies can get to as large as 2.
